Furnace plates of refractory material



Sept. 10, 1957 A. E. MALM FURNACE PLATES OF REFRACTORY MATERIAL 2 Sheets-Sheet 2 Filed May 21, 1954 E m 3 B Timlllilliillll 3i fl i T T Z LE ate trite FURNACE PLATES or REFRACTGRY MATE Application May 21, 1954, erial No. 431,532

1 Claim. (Cl. 266-43) Refractory plates produced by casting or in other manner, such as hearths or dampers of refractory steel for industrial furnaces have, when produced in larger units, a great tendency to deformation and formation of cracks on account of the mechanical interior stresses appearing at temperature differences in the plate. Therefore, it has been found to be suitable to form larger hearths and also dampers for furnaces of a plurality of smaller plates which are joined together to form coherent slabs. The separate plates have a certain movableness in relation to each other which in conjunction with the small dimensions of the plates reduces the interior stresses in the material and thus the tendency to deformation and formation of. cracks. Since below the hearth of a furnace there are often disposed electric heaters which are to be well protected against impurities, such as oxide scales from the material under heat treatment on the hearth, hearths of said mosaic type must be provided with a joint system preventing as much as possible such impurities from falling down on the heaters, which system should therefore have no continuous cavities in the joints.

It has already been proposed (Canadian Patent No. 541,578) to provide a joint system which complies with these requirements. This patent describes a four-sided plate in which each of two adjacent lateral edges is provided with a ledge projecting in the plane of the plate and a ledge projecting from the base of said first ledge at right angles thereto. The other lateral edges of the plate have grooves corresponding to said ledges to enable the plates to be united at their lateral edges to form coherent slabs. When uniting such plates, however, one plate must be put into another from the side, i. e. in the length direction of the ledges and the grooves, and hereby it is not possible to build a hearth for instance on its place in the furnace, but the uniting must take place outside the furnace.

Accordingly, the object of the invention is to provide plates of refractory material, which may be combined to a coherent slab at any place or area which is to be entirely covered with the plates.

Another object of the invention is to provide plates consisting of refractory material and having joints closing substantially tightly at the operating temperature in a furnace.

The invention will be further described hereinafter with reference to the accompanying drawings which show a preferred embodiment.

In the drawings:

Fig. l is a perspective view of a plate, as seen from one side.

Fig. 2 is a perspective view of the same plate, as seen at right angles to Fig. 1.

Fig. 3 shows the plate seen from above.

Fig. 4 shows a section along the line IVIV in Fig. 3.

Fig. 5 shows a section along the line VV in Fig. 3.

Fig. 6 shows a section along the line V1V1 in Fig. 3.

Fig. 7 shows a number of united plates.

Fig. 8 shows a section through the joint between two plates along the line VIE-VIII in Fig. 7, and

Fig. 9 shows a section through another joint between: two plates along the line IXI X in Fig. 7.

As appears especially from the Figs. 1-6 each plate 10 has projecting ledges on two adjacent lateral edges and corresponding grooves formed in extended bottom per-- tions 11 and 12 at the two other edges. One ledge 13' at one edge of the plate projects in the plane of the plate a distance sufi'icient to engage a corresponding groove 14 in another plate (shown by dotted lines in Fig. 6), ir-- respective of a certain clearance which is to be found between the plates, as will be further explained in the following. On the same edge of the plate another ledge 15 projects from the base of the ledge 13 and at right angles thereto to engage a corresponding groove 16 in said other plate. The grooves 14 and 16 are provided at the edge of the plate 19 opposite to the edge carrying said ledges 13 and 15.

The other ledge carrying edge of the plate 10 has one ledge 17 projecting only a smalldistance in the plane of the plate and one ledge 18 projecting from the base of the ledge 17 and at right angles thereto. Corresponding grooves 19 and 20 respectively are provided at opposite edges of the plate. As seen in Figs. 4 and 8 the groove 20 has a greater width than the corresponding ledge 18, whereby a certain clearance is formed between two united plates. When the plates are in cold state, this clearance is at least as great as the height of the ledge 17, but preferably not much wider. The purpose of this is to allow the ledge 17 to pass the upper edge portion 21 of adjacent plate (Fig. 8), when two plates are united in cold state. At the operating temperature in a furnace, for instance, the plates will be extended so that their edges lie close to each other and the ledge 17 is consequently caused to engage its corresponding groove 19 to form a substantially tight joint.

Of course, a certain clearance is also prevailing between the ledges 13, 15 and the grooves 14, 16 to permit the plate to extend also in this direction. As seen in Figs. 5 and 6 the ledges 13 and 15 are tapered somewhat outwardly and the groove 14 is correspondingly tapered inwardly. The groove 16, on the other hand, has a rectangular cross section somewhat wider than the base of the ledge 16. The shapes and positions of the grooves 14, 16 and corresponding ledges 13, 15 make it possible to insert the ledges of one plate in the grooves of another obliquely from above, and said inserted plate may thereafter be swung as a hinge into the plane of adjacent plate, in that the ledge 17 does not prevent such a pivoting movement. In this way it is possible to build a hearth, for instance, directly on its place in a furnace, in that the plates may without difiiculty be assembled to cover the furnace bottom entirely.

The groove 20 adapted to receive the ledge 18 of another plate is limited in its length direction by end walls 22 and 23, as seen in Fig. 2. Of course, the ledge 13 has a corresponding length to fit between said end walls. One of the end walls (wall 22) forms a partition between the grooves 20 and 16, and the other end wall 23 has its upper portion extended out from and in the direction of the groove 29 to form a bridge 24 which projects substantially up to the inside of the ledge 15 (Fig. 2). As seen in Fig. 9, said bridge 24 has for its object to cover a possible space formed between two plates at this corner, so that impurities are here efiectively prevented from falling down on the underlying electric heaters, and for that purpose the bridge overlaps also one end of a ledge or flange 25 which forms the outer wall of the groove 16 in adjacent plate.

What I claim is:

A plate formed from a refractory steel an'd'adapted to be assembled with like plates in industrial furnaces, said plate having a four-sided top, portion and an integral foursided bott'omportion',v two adj oining, sidesv of said bottom portion extending outbeyon'd fthe" periphery of said top portion and the oppositely/disposed: two adjoining sides of-saidtop portion extending'outwardly beyond the periphery of said bottom portion,'each of the outwardlyextendingsides of said bottom portion being 'fo'rrned'wi'th a longitudinal groove and each of the outwardly extendingsidesof the top portion being provided with a downwardly-di'recte'd projection shaped to bevreceived in a grooveofthe bottom portion ofanadjoining plate of'like construction, said top portion sides also being provided with laterally extending tonguesand said grooves in said bottomportion being providedwith adjoining inwardlyextending recesses for reception of saidftongues of an adjoining plae of like construction/the tongue of oneof said top portion sides being provided with a' tapered lower surface and the recess in the side of said plate opposite said tongue with the tapered lower surface being 7 provided with a correspondinglyv tapered upper surface to receivethe tapered tongue of an adjoining plate of like construction, the tongues and grooves and each pro- 4 jection and each recess being dimensioned in such manner that when interengaged at room temperature they provide a continuous seal for the joint between adjacent plates and are free to expand when subjected to elevated temperatur'es encountered in industrial furnaces, each projection having a lesser width than the groove in the opposite side of the plate and the end of one of said grooves adjacent one of the outwardly-extending sides of the, top portion being provided with an end Wall and an elevated bridge portion extending in the direction of the tongue of said last-named side to overlie a portion 'of the side of an adjoining plate of like construction.

References Cited in the file of this patent UNITED STATES PATENTS 7 746,399 Staples Dec. 8, 1903 1,492,685 Hale May 6, 1924 2,156,277 Corbin May 2, 1939 2,490,577 Brown Dec. 6, 1949 FOREIGN PATENTS 570,113 Great Britain June 22, 1945 7 OTHER REFERENCES Norton Refractories, pages 482-488, 3rd ed.=, 1949. 

